If you just look at the model number, you might get the idea that the GeForce GT 540M is a significant upgrade from the other GT 420M found in the original XPS 15. Unfortunately, that’s the problem with model numbers; the reality is the only key differences are in clock speeds (and power requirements). Both the GT 420M and the GT 540M sport the same 96 CUDA cores and a 128-bit DDR3 memory interface; however, the GT 420M comes clocked at 500/1000MHz on the core/shaders while the GT 540M sports a 672/1344MHz clock. The memory also runs at 900MHz instead of 800MHz. The result is up to 34% faster computational performance but only 12.5% more memory bandwidth. That means in practice the L502x should beat the L501x by 10 to 35% in gaming performance, depending on where the bottleneck happens to lie—though it could be higher on games that depend more on the CPU.

Here are the full results at our low, medium, and high default settings. Twenty-four graphs for your viewing pleasure; please, take your time.

Looking at the charts and comparing the L501x with the L502x, the CPU actually appears to be a significant bottleneck at lower quality settings. That starts to go away once we move to medium quality and is largely gone at high quality, and there’s still the question of driver differences. The L502x is 31 to 63% faster than the L501x at our low settings, 12 to 51% faster at medium, and 23-43% faster at high. In general, the L502x is able to handle low to medium detail at the native 1080p resolution; if you want to run at medium to high settings you’ll often have to lower the resolution.

Going back to the ASUS G73SW (GTX 460M) comparison once more, we don’t have results for at low quality on the 460M, but the gap at medium is 6 to 198%—with the small 6% lead coming in StarCraft II, a game that can be extremely CPU limited at lower detail settings. If we remove SC2 from the list, the lead is 49 to 98%, which is more in line with what you’d expect from the GPU differences. At high detail, the lead grows to 58 to 120%—again with SC2 being the smallest difference, though L4D2 is similar in that it’s only a 60% lead for the 460M. So how does a GPU that’s got twice the computational performance and slightly more than double the bandwidth end up 120% faster in some games? The 540M in the XPS 15 comes with 2GB RAM versus 1.5GB in the G73SW, so that’s not the explanation. The likely culprit is Optimus, which can have a bit of a PCIe bandwidth bottleneck at times, though it’s possible there’s just something peculiar in how DiRT 2 does things.

If you’re after a good all-around laptop that can handle most games, the new XPS 15 improves on the old model but it’s often not a big enough change to allow you to run at native resolution with higher quality settings. What it does provide is a smoother experience at reasonable settings. The L501x could hit 30 FPS at 1080p and medium detail in three of our eight test games and the L502x breaks 30FPS with the same settings in five games (Mafia II, Mass Effect 2, and Metro 2033 being the exceptions). At our 900p High defaults, the L501x couldn’t break 30FPS in any of the games, but the L502x gets half the games (DiRT 2, Left 4 Dead 2, Mass Effect 2, and STALKER) above our “minimum desired performance” threshold. Dedicated laptop gamers however will still want more.

We’re still waiting to see where the GT 555M falls in terms of performance, but it should slot in nicely between the 540M and the significantly faster GTX offerings. All of the 540M and lower GPUs get saddled with the same 128-bit memory interface, and without GDDR5 to increase bandwidth there’s a significant bottleneck when you start increasing resolution. GDDR5 unfortunately is power hungry, so for the time being most mobile GPUs are saving it for their high-end SKUs where battery life isn’t a concern. Outside of the GTX line, the GT 555M is one of the few NVIDIA mobile GPUs where you can find GDDR5—and there’s some weird changes in the core and memory interfaces for the two 555M models.

The GT 555M version with GDDR5 uses a 128-bit bus and comes with the same 96 CUDA cores as the 540M, but they’re clocked 12% higher. That means you get 12% more computational performance but 74% more bandwidth compared to the GPU in our L502x. The 192-bit DDR3 version of the 555M has slightly less bandwidth, but it has 144 CUDA cores and accounting for clock speeds it has 17.5% more computational performance than the GDDR5 model—and 32% more computational performance than the 540M. It has less bandwidth than the GDDR5 model, even with a 192-bit memory interface, but still 50% more than the 540M. It looks like the new Alienware M14x will use the 192-bit DDR3 version of the GT 555M, which means gaming performance should be around 40-50% faster than the XPS L502x, and coupled with a 900p LCD upgrade the GT 555M should be just about right for our “High” gaming settings.

The one issue I have with matte is that if you happen to brush against it with an object you can leave a "scar" -- not a scratch, but just a mark in the matte finish. If you have a poorly built laptop where the keyboard or palm rest happens to press against the LCD, that can also cause marking -- on glossy as well, but it's more noticeable on matte. Heck, I have a "scar" on my 30" 3007WFP that happened when I was packing for a move. Yeah, ouch! The old Dell Studio XPS 16 had the other issue, with keyboard marks showing up on the edge-to-edge display cover.

Anyway, having seen both the Clevo P150HM/151HM and the XPS 15 panels side by side, I'd definitely take the matte and run that risk.Reply

I have a Dell 2405 FPW with matte finish. Spent around £800 on it back in the day but don't regret it a bit as it's still a contender - rare even now to find 24" with matte IPS that can go portrait and has a USB hub and card readers built in. Anyhoo, I digress... I also got scars on it once or twice and I couldn't for the life of me 'wipe' them away but if you google around you can find solutions...

Amazingly, I found using a clean (try new) white or colourless rubber on the screen and rubbing gently in the direction of the scar worked. Wipe before and after with a lint free micro-fibre cloth and just a teensy bit of water. It literally made the scar disappear and the monitor looks as new again. I sh1t you not - worth a try.Reply

I've found quite the opposite. My matte displays seem to hold up much better than the glossy. The glossy ones seem to pick up scratches, marks and smudges very easily and they show horribly. The matte finish tends to disguise the little things. Reply

I bought the L502x and love it. One great thing about Optimus is that since the Intel graphics is still used for 2D, Intel Quick Sync is possible with this laptop. It is amazing how fast it can convert video for a laptop.

I guess my main complaint is that I preferred the previous generation keys better over the newer smaller softer keys. Dell has regular sales on XPS laptops which really brings down the cost of this laptop. I got a fully loaded Dell XPS 15 L502x for around $1300 after taxes. Just love love love the 1080p screen.

Oh, and I personally am not a big fan of super thin laptops. They just don't feel right when they are on my lap. I like my keyboard to be raised a little so the thicker body of the l502x suits me just fine. I wish Dell hadn't dropped the 14" model as I would have bought that if it was still available with Sandy Bridge for portability but the 15" is fine.Reply

I had a 17" Dell years ago with a 1080p screen and a 7900GT Go. It did OK, but ultimately, I don't think I would ever buy another 1080p laptop without a high end GPU. If the L502X had a higher GPU option, it would be perfect! I would probably order this laptop with the 768p screen and upgrade to the 540 and play games with max settings at native resolution.Reply

I'm curious if during the test anything like that was noticed.I've just bought a L702x and I have the same problem. Dell replaced my motherboard (not the USB3.0 daughterboard), but the issue - with reduced occurency - is still there.Reply

Is it possible they're going into a power saving state and not coming out of it? I actually don't have any USB3 devices on hand, so I didn't encounter this, but I should be getting something soon. Let me get back to you....Reply

Supposedly, under all programs there is a folder for the usb 3.0 controller and clicking on it will bring up a settings panel for the controller. On that panel there is a disable power management function, checking apparently resolves the issue of the ports becoming unresponsive. I thought that sandy bridge had native support though?Reply